As far as I was aware it never did, is it definitely intended behaviour to send an email?
As per my post in that thread, there was code in the old file, which isn't in the new one, and the user who posted that thread made use of the feature previously. The code I posted came directly from the users module file in the section to activate users, there's literally a language string for the email content.
Hi,
Thank you for your report. We have pushed this issue to our Github repository for further analysis where you can track our commits and progress with fixing this bug. Discussions regarding this bug may also take place there too.
Follow this link to visit the issue on Github:
https://github.com/mybb/mybb/issues/2652
Thanks for contributing to MyBB!
Regards,
The MyBB Group